Further studies on the harvesting of normal granulocytes using selective filtration-pheresis instead of centrifugation-pherisis will be carried out. These will also include an investigation of the viability and funtional properties of the cells. An intensive study of the clinical value of transfusions of filtered granulocytes will be continued. The mechanism of selective adhesion-elution of normal granulocytes will be studied with view of applying the filtration- pheresis approach to the harvesting of other blood elements for the purpose of transfusion. Preservation of normal granulocytes separated by filtration-leukopheresis will also be investigated.